In wireless communication represented by wireless local area networks (LANs) conforming to the IEEE 802.11 standard series, there are many setting items that must be set prior to use.
For example, as setting items, there are communication parameters needed to perform wireless communication, such as the Service Set Identifier (SSID) which is a network identifier, an encryption method, an encryption key, an authentication method, and an authentication key. It is very complicated for the user to manually enter and set these communication parameters.
Therefore, various manufacturers have devised automatic setting methods for easily setting communication parameters in wireless devices. In these automatic setting methods, one device provides communication parameters to another device connected thereto using a procedure and messages determined in advance between these connected devices, and accordingly the communication parameters are automatically set.
Non Patent Citation 1 discloses an example of automatically setting communication parameters. In this example where automatic setting is performed, there are two methods, one involving the user to enter an authentication code to a device (hereinafter called an authentication code method), and the other not involving the user to enter an authentication code (hereinafter called a non-authentication code method) (see Non Patent Citation 1 for details).    Non Patent Citation 1: Wi-Fi CERTIFIED™ for Wi-Fi Protected Setup: Easing the User Experience for Home and Small Office Wi-Fi® Networks, http://www.wi-fi.org/wp/wifi-protected-setup
The authentication code method performs an authentication process between devices using the entered authentication code. If the authentication process is successful, one device provides communication parameters to the other device, and the other device receives the communication parameters. In this case, the devices can securely share the communication parameters by performing the authentication process.
In the non-authentication code method, when a device starting a communication-parameter automatic setting process is detected, communication parameters are automatically provided to the detected device. An example of the non-authentication code method is a method of starting a setting process in response to pressing of a setting start button provided in a device and performing automatic setting with another device that has similarly started a setting process during the setting process (hereinafter called a button pressing method). The non-authentication code method is inferior to the authentication code method in security. However, since the user need not enter the authentication code, the non-authentication code is advantageous in that the operation becomes easier.
As has been described above, the button pressing method automatically sets communication parameters simply by pressing the setting start button provided in a device. Therefore, the button pressing method is suitable for built-in devices with poor user interfaces.
However, when the users of a plurality of devices press the setting start buttons almost at the same time, depending on the positional relationship among the devices, communication parameters may be automatically set in unintended devices.